Performing a desired manipulation of an encoded data slice based on a metadata restriction and a storage operational condition

ABSTRACT

A method comprises receiving a set of write fan out requests for a plurality of sets of encoded data slices and metadata regarding storage parameters for the plurality of sets of encoded data slices. The method continues by identifying an encoded data slice of the plurality of sets of encoded data slices based on a desired manipulation of the encoded data slice. The method continues by determining whether the metadata provides a restriction regarding the desired manipulation of the encoded data slice. When the metadata does not provide the restriction regarding the desired manipulation of the encoded data slice, the method continues by determining whether execute the desired manipulation of the encoded data slice based on a storage operational condition. The method continues by executing the desired manipulation of the encoded data slice when the storage unit determines to execute the desired manipulation of the encoded data slice.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of an embodiment of a write fan outrequest in accordance with the present invention;

FIG. 10 is a schematic block diagram of another embodiment of a writefan out request in accordance with the present invention.

FIG. 11 is a logic diagram of an example of a method of determining ifmetadata restricts a desired manipulation of an encoded data slice inaccordance with the present invention; and

FIG. 12 is a logic diagram of an example of a method of determiningacceptable modifications of an encoded data slice in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each of the managing unit 18 and the integrity processing unit20 may be separate computing devices, may be a common computing device,and/or may be integrated into one or more of the computing devices 12-16and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 and 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data (e.g., data 40) as subsequently described withreference to one or more of FIGS. 3-8. In this example embodiment,computing device 16 functions as a dispersed storage processing agentfor computing device 14. In this role, computing device 16 dispersedstorage error encodes and decodes data on behalf of computing device 14.With the use of dispersed storage error encoding and decoding, the DSN10 is tolerant of a significant number of storage unit failures (thenumber of failures is based on parameters of the dispersed storage errorencoding function) without loss of data and without the need for aredundant or backup copies of the data. Further, the DSN 10 stores datafor an indefinite period of time without data loss and in a securemanner (e.g., the system is very resistant to unauthorized attempts ataccessing the data).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSN memory 22 fora user device, a group of devices, or for public access and establishesper vault dispersed storage (DS) error encoding parameters for a vault.The managing unit 18 facilitates storage of DS error encoding parametersfor each vault by updating registry information of the DSN 10, where theregistry information may be stored in the DSN memory 22, a computingdevice 12-16, the managing unit 18, and/or the integrity processing unit20.

The managing unit 18 creates and stores user profile information (e.g.,an access control list (ACL)) in local memory and/or within memory ofthe DSN memory 22. The user profile information includes authenticationinformation, permissions, and/or the security parameters. The securityparameters may include encryption/decryption scheme, one or moreencryption keys, key generation scheme, and/or data encoding/decodingscheme.

The managing unit 18 creates billing information for a particular user,a user group, a vault access, public vault access, etc. For instance,the managing unit 18 tracks the number of times a user accesses anon-public vault and/or public vaults, which can be used to generate aper-access billing information. In another instance, the managing unit18 tracks the amount of data stored and/or retrieved by a user deviceand/or a user group, which can be used to generate a per-data-amountbilling information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an IO interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the IO deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. The dispersed storage error encodingparameters include an encoding function (e.g., information dispersalalgorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding,non-systematic encoding, on-line codes, etc.), a data segmentingprotocol (e.g., data segment size, fixed, variable, etc.), and per datasegment encoding values. The per data segment encoding values include atotal, or pillar width, number (T) of encoded data slices per encodingof a data segment (i.e., in a set of encoded data slices); a decodethreshold number (D) of encoded data slices of a set of encoded dataslices that are needed to recover the data segment; a read thresholdnumber (R) of encoded data slices to indicate a number of encoded dataslices per set to be read from storage for decoding of the data segment;and/or a write threshold number (W) to indicate a number of encoded dataslices per set that must be accurately stored before the encoded datasegment is deemed to have been properly stored. The dispersed storageerror encoding parameters may further include slicing information (e.g.,the number of encoded data slices that will be created for each datasegment) and/or slice security information (e.g., per encoded data sliceencryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides the data(e.g., a file (e.g., text, video, audio, etc.), a data object, or otherdata arrangement) into a plurality of fixed sized data segments (e.g., 1through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more).The number of data segments created is dependent of the size of the dataand the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 80 is shown inFIG. 6. As shown, the slice name (SN) 80 includes a pillar number of theencoded data slice (e.g., one of 1-T), a data segment number (e.g., oneof 1-Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

FIG. 9 is a schematic block diagram of an embodiment of a write fan outrequest. In this example, a device 100 receives a data segment 102 ofdata. The device 100 disperse storage error encodes the data segment 102using an encoding function (e.g., Cauchy Reed-Solomon) to produce a setof encoded data slices 104 and sends the set of encoded data slices 104and metadata 110 as write fan out requests 108 to a first set of storageunits of one or more sets of storage units. Note that metadata 110includes storage parameters for the plurality of sets of encoded dataslices (e.g., restrictions). The storage units 36 (e.g., SU #1 throughSU #7) receive the write fan out requests 108 and metadata 110 and storethe encoded data slices (e.g., EDS 1_1_1_a 1 through EDS 7_1_1_a 1) andmetadata.

FIG. 10 is a schematic block diagram of another embodiment of a writefan out request. In this example, the first set of storage units of theone or more sets of storage units receives the write fan out requests108 and stores the set of encoded data slices 104 and metadata 110. Forexample, SU #1-1 through SU #7-1 receives a write fan out request 108that includes the set of encoded data slices 104 (e.g., EDS 1_1_1_a 1through EDS 7_1_1_a 1) and metadata 110 and stores the set of encodeddata slices and metadata in memory.

As shown, the first set of storage units, in accordance with the writefan out request, copies the set of encoded data slices 104 and metadata110 and transfers the copied set of encoded data slices and metadata toanother one or more sets of storage units. For example, the first set ofstorage units (e.g., SU #1-1 through SU #7-1) copies the set of encodeddata slices (e.g., EDS 1_1_1_a 1 through EDS 7_1_1_a 1) and metadata inaccordance with the write fan out request 108 and transfers the copiedset of encoded data slices and metadata to another set of storage units(e.g., SU #1-2 through SU #7-2). Note the metadata may vary from encodeddata slice to encoded data slice within the set of encoded data slicesand may vary from each copy of an encoded data slice of each copied setof encoded data slices. For example, metadata for EDS 1_1_1_a 1 storedin SU #1-1 may provide a restriction that the EDS 1_1_1_a 1 stored in SU#1-1 may not be rebuilt in a certain timeframe. However, metadata forthe copy of EDS 1_1_1_a 1 stored in SU #1-2 may not have a restriction,or may have a restriction that the encoded data slice is locked (e.g.,cannot be automatically deleted).

As another example, metadata for EDS 2_1_1_a 1 stored in SU #2-3 mayprovide a restriction locking EDS 2_1_1_a 1 without a limitedmodification (e.g., cannot be deleted, overwritten, updated, rebuild,transferred, etc.), and metadata for EDS 2_1_1_a 1 stored in SU #2-1 mayprovide a restriction with a limited modification (e.g., locked for acertain timeframe (e.g., one hour, within two hours of a next update,etc.). As a yet further example, metadata for EDS 6_1_1_a 1 stored in SU#6-2 may provide a restriction locking EDS 6_1_1_a 1 stored in SU #6-2with limited modification (e.g., cannot delete, but can rebuild,transfer, and update), and metadata for EDS 6_1_1_a 1 stored in SU #6-3may provide no restriction.

FIG. 11 is a logic diagram of an example of a method of determining ifmetadata restricts a desired manipulation of an encoded data slice(EDS). The method begins with step 116, where a first set of storageunits of a dispersed storage network (DSN) receives a set of write fanout requests for a plurality of sets of encoded data slices and metadataregarding storage parameters for the plurality of sets of encoded dataslices. The method continues with step 118, where the first set ofstorage units copy the plurality of sets of encoded data slices inaccordance with the set of write fan out requests to produce one or morecopies of the plurality of sets of encoded data slices.

The method continues with step 120, where the first set of storage unitstransfer the one or more copies of the plurality of sets of encoded dataslices and the metadata to one or more other sets of storage units. Forexample, the first set of storage units identify the one or more othersets of storage units in accordance with the set of write fan outrequests, create one or more copies of the plurality of sets of encodeddata slices in accordance with the set of write fan out requests, andtransfer the one or more copies of the plurality of sets of encoded dataslices to the one or more other sets of storage units in accordance withthe set of write fan out requests.

The method continues with step 122, where a storage unit of the firstset or of the one or more other sets of storage units identifies anencoded data slice of the plurality of sets of encoded data slicesstored by the storage unit based on a desired manipulation (e.g.,rebuild, overwrite, delete, update, etc.) of the encoded data slice. Forexample, the identifying the encoded data slice comprises one or more ofidentifying the encoded data slice as being flagged for rebuilding,identifying the encoded data slice for deletion, identifying the encodeddata slice for overwriting, identifying the encoded data slice for arevision level update, and identifying the encoded data slice for a datatransfer.

The method continues with step 124, where the storage unit determineswhether the metadata provides a restriction regarding the desiredmanipulation of the encoded data slice. For example, the storage unitdetermines the metadata provides a restriction that the encoded dataslice is locked (e.g., cannot be deleted). As another example, thestorage unit determines the metadata provides a restriction with alimited modification that the encoded data slice is locked (e.g., cannotbe deleted), but can be transferred or updated. As yet another example,the storage unit determines the metadata provides a restriction with alimited modification of no rebuilding during certain hours (e.g., 4-7p.m.). As yet another example, the storage unit determines the metadataprovides a restriction of not allowing deletion of the encoded dataslice during the first 4 hours after the encoded data slices has beencreated or stored.

The method branches to step 126 when the storage unit determines themetadata provides a restriction regarding the desired manipulation ofthe encoded data slice. The method continues to step 128 when thestorage unit determines the metadata does not provide a restrictionregarding the desired manipulation of the encoded data slice. The methodcontinues with step 126, where the desired manipulation of the encodeddata slice is restricted.

The method continues with step 128, where the storage unit determineswhether to execute the desired manipulation of the encoded data slicebased on a storage operational condition (e.g., determining howimportant slice is to maintain reliability of set (e.g., number ofcopies of slices, number of redundant slices in the set, number ofslices in the plurality of slices and copies thereof that have neededrebuilding or are lost or corrupted), data access rates, number ofconcurrent requestors, disk failure, running out of available memory, anext update time approaching (e.g., air-dates), etc.).

For example, the storage operational condition comprises one or more of:storage unit reliability (e.g., how often are the storage unitsoff-line, having failure issues), storage unit operational efficiency(e.g., how efficient the storage units are responding to access requestsand latency issues with requestors), dispersed storage error encodingparameters (e.g., decode threshold number, pillar width number,redundancy number, etc.), number of copies of the plurality of sets ofencoded data slices, number of overlapping fulfillment of requests forthe plurality of sets of encoded data slices, and air dates regardingre-run of some encoded data slices of the plurality of sets of encodeddata slice (e.g., re-release of the EDS, new release of next revisionlevel of EDS).

The method branches to step 132 when the storage unit determines not toexecute the desired manipulation of the encoded data slice based on thestorage operational condition. The method continues to step 130 when thestorage unit determines to execute the desired manipulation of theencoded data slice based on the storage operational condition. Themethod continues with step 132 where the storage unit determines toforego, delay or de-prioritize the desired manipulation of the encodeddata slice. For example, the storage unit determines that the desiredmanipulation of the encoded data slice is rebuilding and the metadatadoes not restrict rebuilding. However, the storage unit determines thatbased on a storage operational condition (e.g., a new release of nextrevision level of EDS) is expected to occur within a timeframe andtherefore determines to forego the rebuilding of the encoded data slice.As another example, the storage unit determines that the desiredmanipulation of the encoded data slice is rebuilding and that metadatadoes not restrict rebuilding. However, the storage unit determines thatbased on a storage operational condition (e.g., number of copies of theplurality of sets of encoded data slices) that there are currentlysufficient copies of the encoded data slice and therefore determines todelay the rebuilding of the encoded data slice.

The method continues with step 130, where the storage unit determines toexecute the desired manipulation of the encoded data slice. For example,the storage unit identifies the desired manipulation of the encoded dataslice to be rebuilding. When the metadata does not provide restrictionsregarding rebuilding of the encoded data slice, the storage unitdetermines whether to forego, delay, or de-prioritize rebuilding of theencoded data slice based on the storage operational condition. When thestorage unit determines to forego, delay, or de-prioritize rebuilding ofthe encoded data slice, the storage unit foregoes, delays, orde-prioritizes the rebuilding of the encoded data slice. As anotherexample, the storage unit determines an available storage issue (e.g.,running out of available storage space). The storage unit identifies thedesired manipulation of the encoded data slice to be deleted oroverwritten in response to the available storage issue and when themetadata does not provide restrictions regarding deleting or overwritingof the encoded data slice, the storage unit deletes or overwrites theencoded data slice. As yet another example, the storage unit identifiesthe encoded data slice for data transfer (e.g., as a result of migrationdue to a disk failure). The storage unit then determines whether to skipthe data transfer of the encoded data slice based on the storageoperational condition. The storage unit skips the data transfer of theencoded data slice when the storage unit determines to skip the datatransfer.

FIG. 12 is a logic diagram of an example of a method of determiningacceptable modifications of an encoded data slice. The method beginswith step 140, where the storage unit determines if the metadataprovides a restriction locked with or without a limited modificationrestriction for the desired manipulation of the encoded data slice. Forexample, the storage unit determines that the metadata provides therestriction of locked without modification (e.g., read-only, cannotdelete, etc.). As another example, the storage unit determines that themetadata includes a lock with a limited modification restriction for theencoded data slice (e.g., cannot rebuild or update, but can delete,transfer or overwrite).

The method branches to step 142, when the storage unit determines themetadata provides a restriction locked without a limited modificationrestriction. The method continues to step 144, when the storage unitdetermines the metadata provides a restriction locked with a limitedmodification restriction. The method continues at step 142, where thestorage unit delays or discards the desired manipulation of the encodeddata slice.

The method continues with step 144, where the storage unit determineswhether the desired manipulation of the encoded data slice is anacceptable modification in accordance with the limited modificationrestriction. When the desired manipulation of the encoded data slice isan acceptable modification in accordance with the limited modificationrestriction, the method continues to step 146. When the desiredmanipulation of the encoded data slice is not an acceptable modificationin accordance with the limited modification restriction, the methodbranches to step 148. The method continues to step 146, where thestorage unit executes the desired manipulation of the encoded dataslice. For example, the storage unit identifies an encoded data slice tobe updated. The storage unit determines that metadata of the encodeddata slice provides a restriction with a limited modification (e.g.,cannot delete, but can update) and executes the rebuilding of theencoded data slice.

The method continues at step 148, where the storage unit delays ordiscards the desired manipulation of the encoded data slice. Forexample, the storage unit determines the desired manipulation of anencoded data slice to be deletion, but the metadata provides a lockedwith limited modification restriction of rebuilding, but not deletion inthe first two hours of storage life of the encoded data slice. Thestorage unit delays the desired manipulation until the locked withlimited modification restriction no longer prevents the storage unitdeleting the encoded data slice. As another example, the storage unitdetermines the desired manipulation of an encoded data slice to berebuilding, but the metadata provides a locked with limited modificationrestriction of not rebuilding when there are air dates regarding are-run of some encoded data slices. The storage unit determines thatthere will be air dates regarding the re-run of the encoded data sliceassociated with the desired manipulation and discards the desiredmanipulation of the encoded data slice.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to.” As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method comprises: receiving, by a first set ofstorage units of a dispersed storage network (DSN) and via at least oneinterface of the first set of storage units and from a device via theDSN, a set of write fan out requests for a plurality of sets of encodeddata slices and metadata regarding storage parameters for the pluralityof sets of encoded data slices, wherein a data object is segmented intoa plurality of data segments by the device, wherein a data segment ofthe plurality of data segments is dispersed error encoded by the devicein accordance with dispersed error encoding parameters to produce a setof encoded data slices of the plurality of sets of encoded data slices;copying, by the first set of storage units, the plurality of sets ofencoded data slices in accordance with the set of write fan out requeststo produce one or more copies of the plurality of sets of encoded dataslices; transferring, by the first set of storage units and via the atleast one interface of the first set of storage units via the DSN, theone or more copies of the plurality of sets of encoded data slices andthe metadata to one or more other sets of storage units to be storedwithin the one or more other sets of storage units in accordance withthe set of write fan out requests; identifying, by a storage unit of thefirst set or of the one or more of the other sets of storage units, anencoded data slice of the plurality of sets of encoded data slicesstored by the storage unit based on a desired manipulation of theencoded data slice; determining, by the storage unit, whether themetadata provides a restriction regarding the desired manipulation ofthe encoded data slice; based on a first determination that the metadatadoes not provide the restriction regarding the desired manipulation ofthe encoded data slice, determining, by the storage unit, whether toexecute the desired manipulation of the encoded data slice based on astorage operational condition that is based on at least one of storagereliability, data access rates, disk failure, or available memory ofstorage units associated with the plurality of sets of encoded dataslices; and based on a second determination by the storage unit toexecute the desired manipulation of the encoded data slice, executing,by the storage unit, the desired manipulation of the encoded data slice.2. The method of claim 1, wherein the identifying the encoded dataslices comprises at least one of: identifying the encoded data slice asbeing flagged for rebuilding; identifying the encoded data slice fordeletion; identifying the encoded data slice for overwriting;identifying the encoded data slice for a revision level update; oridentifying the encoded data slice for a data transfer.
 3. The method ofclaim 1 further comprises: determining that the metadata provides therestriction of locked without modification; and delaying or discarding,by the storage unit, the desired manipulation of the encoded data slice.4. The method of claim 1 further comprises: determining that themetadata includes a lock with limited modification restriction for theencoded data slice; determining, by the storage unit, whether thedesired manipulation of the encoded data slice is an acceptablemodification in accordance with the limited modification restriction;when the desired manipulation of the encoded data slice is an acceptablemodification in accordance with the limited modification restriction,executing, by the storage unit, the desired manipulation of the encodeddata slice; and when the desired manipulation of the encoded data sliceis not an acceptable modification in accordance with the limitedmodification restriction, delaying or discarding, by the storage unit,the desired manipulation of the encoded data slice.
 5. The method ofclaim 1 further comprises: identifying the desired manipulation of theencoded data slice to be rebuilding; when the metadata does not providerestrictions regarding rebuilding of the encoded data slice,determining, by the storage unit, whether to forego, delay, orde-prioritize rebuilding of the encoded data slice based on the storageoperational condition; and foregoing, delaying, or de-prioritizing, bythe storage unit, the rebuilding of the encoded data slice when thestorage unit determines to forego, delay, or de-prioritize rebuilding ofthe encoded data slice.
 6. The method of claim 1 further comprises:determining, by the storage unit, an available storage issue;identifying the desired manipulation of the encoded data slice to bedeleted or overwritten in response to the available storage issue; andwhen the metadata does not provide restrictions regarding deleting oroverwriting of the encoded data slice, deleting or overwriting, by thestorage unit, the encoded data slice.
 7. The method of claim 1 furthercomprises: identifying, by the storage unit, the encoded data slice fordata transfer; determining, by the storage unit, whether to skip thedata transfer of the encoded data slice based on the storage operationalcondition; and skipping, by the storage unit, the data transfer of theencoded data slice when the storage unit determines to skip the datatransfer.
 8. The method of claim 1, wherein the storage operationalcondition further comprises at least one of: storage unit reliability;storage unit operational efficiency; dispersed storage error encodingparameters; number of copies of the plurality of sets of encoded dataslices; number of overlapping fulfilment of requests for the pluralityof sets of encoded data slices; or air dates regarding re-run of someencoded data slices of the plurality of sets of encoded data slice. 9.The method of claim 1 further comprises: identifying, by the first setof storage units, the one or more other sets of storage units inaccordance with the set of write fan out requests.
 10. A storage unitcomprises: an interface; memory that stores operational instructions;and a processing module operably coupled to the interface and thememory, wherein the processing module is configured to execute theoperational instructions to: when the storage unit is in a first set ofstorage units of a dispersed storage network (DSN): receive, via theinterface and from a device via the DSN, a write fan out request of aset of write fan out requests for a set of encoded data slices andmetadata regarding storage parameters for the set of encoded dataslices, wherein a data object is segmented into a plurality of datasegments by the device, wherein a data segment of the plurality of datasegments is dispersed error encoded by the device in accordance withdispersed error encoding parameters to produce a set of encoded dataslices of the plurality of sets of encoded data slices, wherein the setof write fan out requests is sent to the first set of storage units;units from a device via the DSN; copy an encoded data slice of the setof encoded data slices in accordance with the write fan out request toproduce one or more copies of the encoded data slice; transfer, via theinterface and via the DSN, the one or more copies of the encoded dataslice and the metadata to one or more other storage units of one or moreother sets of storage units to be stored within the one or more othersets of storage units in accordance with the set of write fan outrequests; identify the encoded data slice based on a desiredmanipulation of the encoded data slice; determine whether the metadataprovides a restriction regarding the desired manipulation of the encodeddata slice; based on a first determination that the metadata does notprovide the restriction regarding the desired manipulation of theencoded data slice, determine whether to execute the desiredmanipulation of the encoded data slice based on a storage operationalcondition that is based on at least one of storage reliability, dataaccess rates, disk failure, or available memory of storage unitsassociated with the plurality of sets of encoded data slices; and basedon a second determination by the storage unit to execute the desiredmanipulation of the encoded data slice, execute the desired manipulationof the encoded data slice.
 11. The storage unit of claim 10, wherein theprocessing module is further configured to execute the operationalinstructions to identify the encoded data slices by at least one of:identifying the encoded data slice as being flagged for rebuilding;identifying the encoded data slice for deletion; identifying the encodeddata slice for overwriting; identifying the encoded data slice for arevision level update; or identifying the encoded data slice for a datatransfer.
 12. The storage unit of claim 10, wherein the processingmodule is further configured to execute the operational instructions to:determine that the metadata provides the restriction of locked withoutmodification; and delay or discard, by the storage unit, the desiredmanipulation of the encoded data slice.
 13. The storage unit of claim10, wherein the processing module is further configured to execute theoperational instructions to: determine that the metadata includes a lockwith limited modification restriction for the encoded data slice;determine, by the storage unit, whether the desired manipulation of theencoded data slice is an acceptable modification in accordance with thelimited modification restriction; and when the desired manipulation ofthe encoded data slice is an acceptable modification in accordance withthe limited modification restriction, execute, by the storage unit, thedesired manipulation of the encoded data slice; and when the desiredmanipulation of the encoded data slice is not an acceptable modificationin accordance with the limited modification restriction, delay ordiscard, by the storage unit, the desired manipulation of the encodeddata slice.
 14. The storage unit of claim 10, wherein the processingmodule is further configured to execute the operational instructions to:identify the desired manipulation of the encoded data slice to berebuilding; when the metadata does not provide restrictions regardingrebuilding of the encoded data slice, determine, by the storage unit,whether to forego, delay, or de-prioritize rebuilding of the encodeddata slice based on the storage operational condition; and forego,delay, or de-prioritize, by the storage unit, the rebuilding of theencoded data slice when the storage unit determines to forego, delay, orde-prioritize rebuilding of the encoded data slice.
 15. The storage unitof claim 10, wherein the processing module is further configured toexecute the operational instructions to: determine, by the storage unit,an available storage issue; identify the desired manipulation of theencoded data slice to be deleted or overwritten in response to theavailable storage issue; and when the metadata does not providerestrictions regarding deleting or overwriting of the encoded dataslice, delete or overwrite, by the storage unit, the encoded data slice.16. The storage unit of claim 10, wherein the processing module isfurther configured to execute the operational instructions to: identify,by the storage unit, the encoded data slice for data transfer;determine, by the storage unit, whether to skip the data transfer of theencoded data slice based on the storage operational condition; and skip,by the storage unit, the data transfer of the encoded data slice whenthe storage unit determines to skip the data transfer.
 17. The storageunit of claim 10, wherein the processing module is further configured toexecute the operational instructions to determine the storageoperational condition by at least one of: storage unit reliability;storage unit operational efficiency; dispersed storage error encodingparameters; number of copies of the plurality of sets of encoded dataslices; number of overlapping fulfilment of requests for the pluralityof sets of encoded data slices; or air dates regarding re-run of someencoded data slices of the plurality of sets of encoded data slice. 18.The storage unit of claim 10, wherein the processing module is furtherconfigured to execute the operational instructions to: identify, by thefirst set of storage units, the one or more other sets of storage unitsin accordance with the set of write fan out requests.